Fluid duct

1. A fluid duct ( 2 ) comprising a tubular base wall ( 11 ) surrounding a duct channel and at least one bellows ( 10 )

formed along a section of the tubular base wall ( 11 ), the bellows ( 10 ) comprising a plurality of convolutes ( 12 ) having a profile ( 14 ) projecting radially from the tubular base wall ( 11 ), wherein at least one of said plurality of convolutes ( 12 ) wraps around the duct channel with a wrap-around angle Ω of between 360° and 720° measured from a first end ( 22 a ) to a second end ( 22 b ), the vertex of the wrap-around angle Ω at a centerline C of the duct channel, said second end ( 22 b ) being offset in a flow direction F parallel to the centerline C of the duct channel by a non-zero offset distance D from the first end; and wherein the bellows ( 10 ) is provided on a bent section ( 8 ) of fluid duct ( 2 ), wherein the convolutes ( 12 ) are oriented such that overlapping end portions ( 23 a , 23 b ) of each convolute ( 12 ) are provided on an outer radius of the bent section ( 8 ).

2. The fluid duct according to claim 1 , wherein the fluid duct further comprises at least one different bellows ( 10 ) comprising convolutes ( 12 ) that wrap around the duct channel by a second wrap-around angle Ω between 180° and 360°, said convolutes ( 12 ) being arranged in pairs that interleave such that the convolutes ( 12 ) of the pair wind around the duct channel in opposite winding directions.

3. The fluid duct according to claim 2 , wherein the second wrap-around angle Ω is in a range of 200° to 340°.

4. The fluid duct according to claim 3 , wherein said at least one different bellows ( 10 ) comprising interleaving pairs of convolutes ( 12 ) is on a straight or substantially straight section ( 9 ) of fluid duct ( 2 ).

5. The fluid duct according to claim 2 , wherein said at least one different bellows ( 10 ) comprising interleaving pairs of convolutes ( 12 ) is on a straight or substantially straight section ( 9 ) of fluid duct ( 2 ).

6. The fluid duct according to claim 1 , wherein the convolutes ( 12 ) wrap around the duct channel by a wrap-around angle Ω of between 380° and 560°.

7. The fluid duct according to claim 1 , wherein said convolutes ( 12 ) of said at least one bellows ( 10 ) are provided in a juxtaposed manner.

8. The fluid duct according to claim 7 , wherein ends ( 22 a , 22 b ) of the juxtaposed convolutes ( 12 ) are substantially aligned along a virtual line that is substantially parallel to the centerline C of the duct channel.

9. The fluid duct according to claim 7 , wherein the juxtaposed convolutes ( 12 ) are arranged in a manner rotated one with respect to the other around the centerline C of the duct channel.

10. The fluid duct according to claim 1 , wherein the convolutes ( 12 ) are each provided with at least one narrowing taper ( 16 ) having an axial width W′ that is smaller than a width W of a non-narrowed, non-tapered portion of the convolute ( 12 ); a radial height H′ that is smaller than a radial height H of a non-narrowed, non-tapered portion of the convolute ( 12 ); or wherein W′ and H′ are smaller than W and H, respectively.

11. The fluid duct according to claim 10 , wherein the narrowing taper ( 16 ) is arranged in an oblique section of the convolute ( 12 ).

12. The fluid duct according to claim 10 , wherein the narrowing taper ( 16 ) is provided midway between ends ( 22 a , 22 b ) of the convolute ( 12 ).

13. The fluid duct according to claim 1 , wherein the profile ( 14 ) of said convolutes ( 12 ) is convex and protrudes radially outwardly from the tubular base wall ( 11 ).

14. The fluid duct according to claim 1 , for use as a fluid duct in an automotive engine compartment.

15. The fluid duct according to claim 1 , wherein the fluid duct ( 2 ) is a blow molded or extruded polymer component.